The present invention relates to the field of impulse ink jet inks, and more particularly to the field of impulse ink jet inks for use in impulse ink jet systems having metallic materials which are in contact with and subject to corrosion by such inks.
A wide variety of impulse ink jet inks have been suggested. As disclosed in the aforementioned related patents and patent applications, these inks may comprise a wide variety of materials including fatty acids, such as oleic acids; a wide variety of colorants, including many dyes and several pigments; and solvents and solvent additives including aromatic alcohols, aromatic ethers, dimethylsulfoxides, alkyl pyrrolidones, methoxy- and ethoxy- triglycols, and aliphatic ketones, and in particular n-methyl pyrrolidone, benzyl alcohol, benzyl ether, diethylene glycol, methoxy triglycol, and mixtures thereof.
In addition to the above, other practitioners in the art have suggested the use of various materials in inks, including inks intended for certain types of ink jet printing. In U.S. Pat. No. 4,197,135 (Bailey et al.), inks are disclosed containing a water soluble dye and a polyamine containing 7 or more nitrogen atoms per molecule which is said to improve the water-fastness of inks to be used in ink jet printing. Bailey et al. further discloses that the additives of his invention are to be distinguished from the polyethyleneemines of the prior art in that none of the emine functionalities are primary in order to avoid an azo dye composition reaction, which requirement may be met by synthesis of peralkyl or perhydroxyalkyl substituted polyethylene amines. The preferred polyamines are disclosed as having the hydrogen of the primary amine group replaced with either a methyl or a hydroxyethyl group.
In U.S. Pat. No. 4,343,653 (Beach et al.), jet inks are disclosed comprising sulfur black 1 dyes, the solublizing groups of which have been oxidized, as for example through the use of hydrogen peroxide.
In U.S. Pat. No. 4,382,946, entitled "Ink Composition For Ink-Jet Recording" (Uehara et al.), an ink having an aqueous solution comprising a water soluble acid or direct dye or mixtures thereof is disclosed which further comprises a compound selected from the class of polyhydric alcohols having 1-6 carbon atoms, hexylene glycol, triethylene glycol, di-propylene glycol and 1,2,6-hexanetriol.
U.S. Pat. No. 4,409,040 (Tabayashi et al.) discloses a wide variety of ink jet inks including those containing a variety of solubilizing or wetting agents. In particular, Tabayashi suggests an ink comprising a solution in water of a water-soluble dye, a wetting agent and polyethylene glycol phenol ether or its derivatives. Examples of the disclosd wetting agent including polyhydric alcohols such as ethylene glycol, diethylene glycol, glycerol, triethylene glycol, tetraethylene glycol, polyethylene glycols, polypropylene glycol, pyrrolidones including n-methyl pyrrolidone and beta-hydroxyethylpyrrolidone, low molecular weight alkyleneimines such as polyethyleneimine and polypropyleneimine; aminoalcohols such as monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine and aminoethylethanolamine and amides such as formamide and N,N-dimethylformamide.
Additional patents of interest in this area include U.S. Pat. Nos. 3,282,853, (Bennett); 4,108,671 (Richlin); 4,136,076 (Daniels); 4,150,997 (Hayes); 4,153,467 (Yano); and 4,279,653 (Makishima et al.). In U.S. Pat. No. 4,279,653, (Makishima et al.), an ink composition for ink jet recording is disclosed consisting essentially of a water-soluble wetting agent, water, a water-soluble dye and an "oxygen absorber". Makishima teaches that where amounts of dissolved air in ink is large, the higher the frequency of repetition of increase of pressure, "the more the ink comes to have properties as a compressible fluid and the more the transfer of increase of the pressure is delayed". Accordingly, Makishima teaches the desirability of maintaining amounts of dissolved air at a very low level. Physical or chemical methods for removing dissolved oxyge are thus suggested, which include reacting the oxygen dissolved in an ink with oxygen absorbing compounds including metals such as iron chips; sulfites such as sodium sulfite, ammonium sulfite, potassium sulfite, sodium hydrogen sulfite; potassium hydrogen sulfite and ammonium hydrogen sulfite, polyhydric phenols such as pyrogallol, and other reducing agents such as sodium trithionite and hydrazine.
Notwithstanding the numerous inks suggested for use in ink jet printing, a need remains to provide ink jet inks which are readily jettable by impulse ink jet systems, which produce high quality prints, and which exhibit superior material compatibilities. The selection of materials used in an ink jet printing system is very crucial to its reliability and performance. The interaction between ink and hardware is a primary concern when selecting materials for hardware or ink.
Most ink jet hardware consists of two major classes of material, metal and polymer. The failure of metal is usually caused by corrosion, while polymeric failure is generally the result of the failure of mechanical properties such as swelling, embrittleness, softness and disintegration.
Applicants have recognized that metal-corrosion can be predicted by electrochemical experiments such as potentiostatic measurement or by weight loss. The corrosion of metal is caused by the transfer of electric charge. Since water can ionize dye and salt impurities, aqueous inks have higher electric conductivity than non-aqueous inks. Hence, aqueous inks are generally more corrosive. Applicants have found that corrosion is seldom caused by the ink vehicle alone, except for a few high ionization polar solvents such as acids or amines.